Hasn't almost everyone used this phrase at least once in their lives? If not, I would be really surprised.
It does definitely makes sense. It's no use worrying about something that will happen in the future and when you have no control over it. If you have no control over that future occurrence then, of course, you can hardly do anything about it. What you can do is to get yourself ready for the eventuality.
It is crazy when people tell me that they don't want to worry about something in the future. I always thought that it is best to be prepared for any eventuality. Yes, you will only need to face the situation if it happens but what if it does and you are not prepared? Doesn't it make sense to be prepared?
To use the same phrase, what if the bridge is broken when you come it and you don't have just the tools necessary to fix it yourself? What if you already knew that you would need those tools to fix that broken bridge?
Worrying about some event that might or might not happen does not do anyone any good. However, according to me, it is crucial that one is prepared for it and is ready to overcome those challenges as he comes to face them. At least, he is not taken by surprise!